1. Technical Field
The present invention relates to the production and improvement of a protective layer of a magnetic disk medium, and in particular, relates to a carbon-based protective layer for a magnetic recording medium and a method for forming the protective layer.
2. Background Information
Magnetic recording media are widely used to provide large-capacity data storage. A magnetic recording medium is generally made of a substrate, a magnetic recording layer and other layers (e.g. soft magnetic backing layer, nonmagnetic intermediate layer, etc.) disposed on the substrate, and a protective layer formed thereon. A lubricate layer may be further formed on the protective layer. The protective layer typically has high wear resistance to withstand the rubbing contact with a magnetic head during operations of the recording medium. It also has high corrosion resistance to prevent the underlying magnetic recording layer from corrosion.
To enhance the recording density and increase the storage capacity of a magnetic recording medium, it is often necessary to decrease the spacing between a magnetic head and the magnetic recording medium when the medium is accessed by the magnetic head—this requires not only a reduction in the flying height of the magnetic head but also a decrease in the thickness of the protective layer of the recording medium. As an example, a carbon-based protective layer of a magnetic recording medium may have a thickness of about 2 nm when it is formed by a PECVD (Plasma-Enhanced Chemical Vapor Deposition) process.
However, when the thickness of the protective layer of the recording medium is reduced, it is often difficult to maintain mechanical durability and weatherability of the recording medium, and to prevent the occurrence of bit errors caused by magnetic corrosion. Thus, it is desirable to form on a magnetic recording medium a thin protective layer that still has high wear and corrosion resistance, so that a magnetic head can fly smoothly over and closely to the magnetic recording medium, to thereby increase the recording density of the recording medium and improve the data transfer speed therebetween.